ABSTRACT
ADSL
Assymetric Digital Subscriber Line
ADSL can practically transform the existing public information network from one limited to voice, text and low resolution graphics to a powerful, ubiquitous system capable of carrying multimedia, including full motion video, to everyone's home.
ADSL works by splitting the phone line into two frequency ranges. The frequencies below 4 kHz are reserved for voice, and the range above that is used for data.
ADSL provides always-on high-speed Internet access over a single dedicated telephone line; cable modems offer always-on high-speed Internet access over a shared cable television line. While cable modems have greater downstream (from the Internet into the home) bandwidth capabilities, that bandwidth is shared among all users in a neighbourhood, and will therefore vary, perhaps dramatically, as more users in a neighbourhood get online at the same time to compete for bandwidth.
With ADSL, even though both the computer and phone require the same line, both can still operate at the same time as the other. This means that users can leave their Internet connection open, and still use the phone line for voice calls.
Speed is one of the main reasons for upgrading from a slower dial up connection. ADSL can reach speeds that are 25 times faster than a dial-up Modem. This means faster surfing, faster downloads, and faster games.
ADSL is a distance-sensitive technology.
A connection that's up to 25x times faster will let you use the Internet as it was meant to be. Web pages will snap up on your screen right away, files will download with amazing speed, and you'll be able to play network games smoothly. The DSL connection is a dedicated link. Unlike ISDN and analogue modem connections the DSL connection is up 24 hours a day. This gives you some additional options like running servers.
On March 6, 2002, it was announced that DSL deployment reached 18.7 million subscribers worldwide at the end of 2001.
DSL will not become outdated for quite some time. As long as copper telephone wires are used for transporting data, and voice, DSL will be a viable technology. ADSL is competing with technologies such as cable-modem access for high-speed connections from consumers to the Internet.
ADSL
Assymetric Digital Subscriber Line
ADSL can practically transform the existing public information network from one limited to voice, text and low resolution graphics to a powerful, ubiquitous system capable of carrying multimedia, including full motion video, to everyone's home.
Nisha.k
S7 IT
1. DSL: An Introduction to ADSL
1.1. What is it?
1.2. What different types are there?
2. The Inner Workings
2.1. What is it?
2.2. How it works
2.2.1. POTS
2.2.2. Modems
2.2.3. Signal Splitting
2.2.4. CAP
2.2.5. DMT
2.2.6.Low-Pass Filter
2.3. DSL Hardware/equipment
2.3.1. DSL Transceiver
2.3.2. DSLAM
3.Various Applications of Adsl
4. Competitors And Comparison
4.1. How it compares
4.2. The strengths
4.2.1. Always-On Service
4.2.2. Phone/Internet Simultaneousl
4.2.3. Speed
4.2.4. Dedicated Connection
4.2.5. Existing infrastructure
4.2.6. Costs are incremental
4.2.7. Integrated diagnostics and maintenance features
4.3. The weaknesses
4.3.1. Maximum range
4.3.2. Asynchronous
4.3.3. Not available everywhere
5. The Current & Future Status
5.1. The current uses
5.2. The current usage
5.3. The future of ADSL
1. DSL: An Introduction to ADSL
1.1. What is it?
Digital Subscriber Line (DSL) is a technology that brings high bandwidth information to homes and small businesses over the existing 2 wire copper telephone lines.
->ADVANTAGES
-uses existing phonelines
-digital data is transmitted directly
->ANALOG TRANSMISSION
->DSL SPEED
1.2. What different types are there?
xDSL refers to different variations of DSL, such as ADSL, SDSL, HDSL, and RADSL.
2. The Inner Workings
2.1. What is it?
->broadband communication technology
->asymmetry
->downstream and upstream speeds
WHY ADSL WAS DESIGNED?
->SOHO services
->to operate simultaneously with POTS
HISTORY
FIGURE
2.2. How it works
->Matches particular frequencies to specific tasks
2.2.1. POTS-PLAIN OLD TELEPHONE SERVICE
2.2.2. Modems
->ADSL MODEMS-ADSL modems "piggyback" their signals on top of the voice signal.
2.2.3. Signal Splitting
ADSL works by splitting the phone line into two frequency ranges.
2.2.4. CAP(CARRIER-LESS AMPLITUDE MODULATION)
->0-4 KHZ
->UPSTREAM TRANSMISSION
->DOWNSTREAM TRANSMISSION
->CHANNELS ARE WIDELY SEPARATED
2.2.5. DMT
2.2.6. Low-Pass Filter
2.3. DSL Hardware/equipment.
ADSL uses two pieces of equipment, one on the customer end and one at the Internet service provider, Telephone Company or other provider of DSL services.
2.3.1. DSL transceiver
it's the point where data from the user's computer or network is connected to the DSL line.
2.3.2. DSLAM(Digital subscriber line access multiplexer)
->receives customer connections
figure
3.various applications of ADSL
->EDUCATION
->VIDEO CONFERENCING
->REAL ESTATE PROFESSIONALS
The following is a comparison of download speeds between ADSL modems and other modems:
Modem Type Download Speed (for a short video – 7.5 MB)
6 Mbps ADSL / 10 sec1.5 Mbps ADSL / 40 sec
1.5 Mbps Cable / 40 sec
128 Kbps ISDN / 7 mins
28.8 Kbps / 35 mins
14.4 Kbps / 71 mins
4.Competitors & Comparison
->data transmission rates are 300 times faster than analog modems
->does away with congestion problems
4.1Comparison with cable modems
4.2. The strengths
4.2.1. Always-On Service
4.2.2. Phone/Internet Simultaneously
4.2.3 Speed
4.2.4 Dedicated Connection
4.2.5 Existing infrastructure
4.3. The weaknesses
4.3.1. Maximum range
4.3.2. Asynchronous
4.3.3. Not available everywhere
5. The Current & Future Status
5.1. The current uses
->A connection that's up to 25x times faster than dial-up modems
->available 24 hours